On Tue, Mar 08, 2011 at 12:22:56AM +0100, Marcin Slusarz wrote: > On Tue, Mar 08, 2011 at 08:24:26AM +1000, Ben Skeggs wrote: > > On Mon, 2011-03-07 at 18:18 +0000, Maarten Maathuis wrote: > > > On Fri, Mar 4, 2011 at 4:49 PM, Marcin Slusarz <[email protected]> > > > wrote: > > > > On Sun, Feb 13, 2011 at 09:38:04PM +0100, Marcin Slusarz wrote: > > > >> Combination of locking and interchannel synchronization changes > > > >> uncovered poor behaviour of nouveau_fence_wait, which on HZ=100 > > > >> configuration could waste up to 10 ms per call. > > > >> Depending on application, it lead to 10-30% FPS regression. > > > >> To fix it, shorten thread sleep time to 0.1 ms and ensure > > > >> spinning happens for at least one *full* tick. > > > >> > > > >> Signed-off-by: Marcin Slusarz <[email protected]> > > > >> --- > > > >> drivers/gpu/drm/nouveau/nouveau_fence.c | 10 ++++++++-- > > > >> 1 files changed, 8 insertions(+), 2 deletions(-) > > > >> > > > >> diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c > > > >> b/drivers/gpu/drm/nouveau/nouveau_fence.c > > > >> index 221b846..75ba5e2 100644 > > > >> --- a/drivers/gpu/drm/nouveau/nouveau_fence.c > > > >> +++ b/drivers/gpu/drm/nouveau/nouveau_fence.c > > > >> @@ -27,6 +27,9 @@ > > > >> #include "drmP.h" > > > >> #include "drm.h" > > > >> > > > >> +#include <linux/ktime.h> > > > >> +#include <linux/hrtimer.h> > > > >> + > > > >> #include "nouveau_drv.h" > > > >> #include "nouveau_ramht.h" > > > >> #include "nouveau_dma.h" > > > >> @@ -230,9 +233,12 @@ int > > > >> __nouveau_fence_wait(void *sync_obj, void *sync_arg, bool lazy, bool > > > >> intr) > > > >> { > > > >> unsigned long timeout = jiffies + (3 * DRM_HZ); > > > >> - unsigned long sleep_time = jiffies + 1; > > > >> + unsigned long sleep_time = jiffies + 2; > > > >> + ktime_t t; > > > >> int ret = 0; > > > >> > > > >> + t = ktime_set(0, NSEC_PER_MSEC / 10); > > > >> + > > > >> while (1) { > > > >> if (__nouveau_fence_signalled(sync_obj, sync_arg)) > > > >> break; > > > >> @@ -245,7 +251,7 @@ __nouveau_fence_wait(void *sync_obj, void > > > >> *sync_arg, bool lazy, bool intr) > > > >> __set_current_state(intr ? TASK_INTERRUPTIBLE > > > >> : TASK_UNINTERRUPTIBLE); > > > >> if (lazy && time_after_eq(jiffies, sleep_time)) > > > >> - schedule_timeout(1); > > > >> + schedule_hrtimeout(&t, HRTIMER_MODE_REL); > > > >> > > > >> if (intr && signal_pending(current)) { > > > >> ret = -ERESTARTSYS; > > > >> -- > > > >> 1.7.4.rc3 > > > >> > > > > > > > > ping again > > > > _______________________________________________ > > > > Nouveau mailing list > > > > [email protected] > > > > http://lists.freedesktop.org/mailman/listinfo/nouveau > > > > > > > > > > This looks ok to me, but I would like to get Ben Skeggs ok on this one > > > as well. So i've CC'ed him, hopefully he'll notice :-) > > Ah sorry, I have actually looked at this quite a while back but came to > > no solid conclusion. > > > > While yes, I did see some minor performance improvement from it, I also > > notice that now we once again get 100% CPU usage while an app is waiting > > for the GPU a lot.. > > It's not "minor" performance improvement: > > without this patch (FPS): > nexuiz: 53 > wop: 181 > tremulous: 157 > wsw0.5: 89 > glxgears: 730 > > with: > nexuiz: 63 (+18%) > wop: 248 (+37%) > tremulous: 156 (-0.6%) > wsw0.5: 91 (+2%) > glxgears: 1054 (+44%) > > > Ok, so you are worried about CPU usage... Let's see what will happen if > I remove spinning added by "drm/nouveau: Spin for a bit in > nouveau_fence_wait() before yielding the CPU". > > reduced version (attached): > nexuiz: 62 > wop: 248 > trem: 157 > wsw0.5: 90 > glxgears: 1055 > > Good enough?
Just for comparison: kernel 2.6.37 + pre nvc0fied mesa had: nexuiz: 34 wop: 139 tremulous: 82 wsw0.5: 53 glxgears: 1056 > --- > From: Marcin Slusarz <[email protected]> > Subject: [PATCH] drm/nouveau: fix __nouveau_fence_wait performance regression > > Combination of locking and interchannel synchronization changes > uncovered poor behaviour of nouveau_fence_wait, which on HZ=100 > configuration could waste up to 10 ms per call. > Depending on application, it lead to 10-30% FPS regression. > > To fix it, shorten thread sleep time to 0.1 ms. > > Additionally, remove spinning (added by "drm/nouveau: Spin for > a bit in nouveau_fence_wait() before yielding the CPU"), because > it's not needed anymore. > > Signed-off-by: Marcin Slusarz <[email protected]> > --- > drivers/gpu/drm/nouveau/nouveau_fence.c | 11 ++++++++--- > 1 files changed, 8 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c > b/drivers/gpu/drm/nouveau/nouveau_fence.c > index a244702..010243b 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_fence.c > +++ b/drivers/gpu/drm/nouveau/nouveau_fence.c > @@ -27,6 +27,9 @@ > #include "drmP.h" > #include "drm.h" > > +#include <linux/ktime.h> > +#include <linux/hrtimer.h> > + > #include "nouveau_drv.h" > #include "nouveau_ramht.h" > #include "nouveau_dma.h" > @@ -229,9 +232,11 @@ int > __nouveau_fence_wait(void *sync_obj, void *sync_arg, bool lazy, bool intr) > { > unsigned long timeout = jiffies + (3 * DRM_HZ); > - unsigned long sleep_time = jiffies + 1; > + ktime_t t; > int ret = 0; > > + t = ktime_set(0, NSEC_PER_MSEC / 10); > + > while (1) { > if (__nouveau_fence_signalled(sync_obj, sync_arg)) > break; > @@ -243,8 +248,8 @@ __nouveau_fence_wait(void *sync_obj, void *sync_arg, bool > lazy, bool intr) > > __set_current_state(intr ? TASK_INTERRUPTIBLE > : TASK_UNINTERRUPTIBLE); > - if (lazy && time_after_eq(jiffies, sleep_time)) > - schedule_timeout(1); > + if (lazy) > + schedule_hrtimeout(&t, HRTIMER_MODE_REL); > > if (intr && signal_pending(current)) { > ret = -ERESTARTSYS; > -- > 1.7.4.rc3 > _______________________________________________ Nouveau mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/nouveau
